EP1361512B1 - Method to synchronize and upload an offloaded network stack connection with a network stack - Google Patents

Method to synchronize and upload an offloaded network stack connection with a network stack Download PDF

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Publication number
EP1361512B1
EP1361512B1 EP03009321A EP03009321A EP1361512B1 EP 1361512 B1 EP1361512 B1 EP 1361512B1 EP 03009321 A EP03009321 A EP 03009321A EP 03009321 A EP03009321 A EP 03009321A EP 1361512 B1 EP1361512 B1 EP 1361512B1
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Prior art keywords
layer
state
peripheral device
variable
delegated
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German (de)
English (en)
French (fr)
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EP1361512A3 (en
EP1361512A2 (en
Inventor
James Pinkerton
Abolade Gbadegesin
Sanjay Kaniyar
Nk Srinivas
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Microsoft Corp
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Microsoft Corp
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L69/00—Network arrangements, protocols or services independent of the application payload and not provided for in the other groups of this subclass
    • H04L69/16—Implementation or adaptation of Internet protocol [IP], of transmission control protocol [TCP] or of user datagram protocol [UDP]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L69/00—Network arrangements, protocols or services independent of the application payload and not provided for in the other groups of this subclass
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L69/00—Network arrangements, protocols or services independent of the application payload and not provided for in the other groups of this subclass
    • H04L69/10—Streamlined, light-weight or high-speed protocols, e.g. express transfer protocol [XTP] or byte stream
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L69/00—Network arrangements, protocols or services independent of the application payload and not provided for in the other groups of this subclass
    • H04L69/16—Implementation or adaptation of Internet protocol [IP], of transmission control protocol [TCP] or of user datagram protocol [UDP]
    • H04L69/161—Implementation details of TCP/IP or UDP/IP stack architecture; Specification of modified or new header fields
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L69/00—Network arrangements, protocols or services independent of the application payload and not provided for in the other groups of this subclass
    • H04L69/16—Implementation or adaptation of Internet protocol [IP], of transmission control protocol [TCP] or of user datagram protocol [UDP]
    • H04L69/166—IP fragmentation; TCP segmentation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L69/00—Network arrangements, protocols or services independent of the application payload and not provided for in the other groups of this subclass
    • H04L69/30—Definitions, standards or architectural aspects of layered protocol stacks
    • H04L69/32—Architecture of open systems interconnection [OSI] 7-layer type protocol stacks, e.g. the interfaces between the data link level and the physical level

Definitions

  • This invention relates generally to methods for increasing the efficiency, speed, and/or throughput of a computer system and, more particularly, relates to methods for synchronizing and uploading computing tasks typically performed by a host processor that have been offloaded to a specific hardware component
  • Various functions that are performed on a data packet as it proceeds between layers can be software intensive, and often requires a substantial amount of CPU processor and memory resources.
  • certain functions that are performed on the packet at various layers are extremely CPU intensive, such as packet checksum calculation and verification, encryption and decryption of data (e.g., SSL encryption and IP Security encryption), message digest calculation, TCP segmentation, TCP retransmission and acknowledgment (ACK) processing, packet filtering to guard against denial of service attacks, and User Datagram Protocol (UDP) packet fragmentation.
  • packet checksum calculation and verification e.g., SSL encryption and IP Security encryption
  • message digest calculation e.g., TCP segmentation, TCP retransmission and acknowledgment (ACK) processing
  • ACK TCP retransmission and acknowledgment
  • UDP User Datagram Protocol
  • NICs network interface cards
  • peripherals are often equipped with a dedicated processor and memory that are capable of performing many of the tasks and functions that are otherwise performed by the CPU.
  • offload mechanisms are limited in that the mechanisms have a secondary requirement that a minimum number of changes be made to the network stack. As a result of this secondary requirement, another limitation is that the offloads have a long code path because the entire network stack is traversed with the offloaded tasks and functions disabled to reach the peripheral device. A further limitation is the lack of integration with the network stack. There is no well defined interface for the network stack to query or set parameters on the peripheral device or an interface for the peripheral device to inform the network stack of any notifications or changes of capabilities. For example, if the route changes when an LSO request is being processed, the fallback mechanism is for the stack to wait for timeouts and retransmit the LSO request.
  • NIC network interface card
  • IP Internet Protocol
  • ICMP Internet Control Message Protocol
  • DNS Domain Name Server
  • RIP RIP
  • US 2001/0027496 A1 relates to an apparatus including a host and a communication processing device (CPD) that is integrated into a host.
  • CPD communication processing device
  • a connection context has been created, which summarizes various features of the connection, such as protocol type and source and destination addresses for each protocol layer.
  • the context may be passed between an interface for the session layer and the CPD, and stored as a communication control block (CCB) at either the CPD or storage of the host.
  • CCB communication control block
  • data received by the CPD from the network and pertaining to the connection is referenced to that CCB and can then be sent directly to the storage of the host according to a fast-path, bypassing sequential protocol processing by the data link, network and transport layers.
  • the CPD removes lower layer headers and sends the remaining application data from the frame directly into its final destination in the host using direct memory access (DMA) units of the CPD.
  • DMA direct memory access
  • the CCB includes control and state information pertinent to all protocols that would have been processed had conventional software layer processing been employed.
  • WO 02/27519 A1 relates to an intelligent network storage interface system including a host which is connected to an INIC (intelligent network interface card) by an I/O bus, such as a PCI bus, which is coupled to the host bus by a host I/O bridge.
  • INIC intelligent network interface card
  • I/O bus such as a PCI bus
  • a connection with a remote host is first set up, which may include handshake, authentication and other connection initialization procedures.
  • a communication control block (CCB) is created by the protocol stack of the host during connection initialization procedures for connection-based messages.
  • the CCB includes connection information, such as source and destination addresses and ports.
  • the CCB also maintains state information regarding the message.
  • the present invention provides a method to offload a network stack connection, such as a TCP based protocol stack.
  • Data that would normally be sent through a NDIS (network driver interface specification) path that has multiple software layers to a peripheral device is offloaded to a path from a switch layer to the peripheral device. Tight synchronization with the network stack and processing unit is maintained
  • a request to offload the stack is sent through the NDIS path to the peripheral device.
  • the request includes a list of resource requirements so that the peripheral device has the information needed to allocate resources.
  • Each layer in the NDIS path adds its resource requirements to the list If the peripheral device accepts the request, the peripheral device allocates resources and sends an offload handle to each of the software layers so that the software layers can communicate with the peripheral device.
  • the state for each software layer is sent to the peripheral device once the peripheral device's acceptance of the offload is communicated to the software layer. Alternatively, the state is sent with the offload request and only changes to the state are sent to the peripheral device.
  • Each state has state variables and each state variable is classified as a constant variable, a cached variable, or a delegated variable. The constant variables do not change during the time the protocol stack is offloaded. Cached variables are handled by the CPU and delegated variables are handled by the peripheral device.
  • the present invention also provides a method to upload an offloaded network connection from the peripheral device to the host
  • the upload is initiated by either the peripheral device or the switch layer. Once the upload is initiated, the peripheral device completes all outstanding requests and hands the delegated state to the switch layer. After the delegated state has been accepted by the host, the state resources at the peripheral device are freed.
  • an update e.g., ARP update or RIP update
  • a sequence number is used to ensure that the most recent update message is used if multiple update messages are received by the peripheral device so that the peripheral device does not use stale data.
  • Figure 1 is a block diagram generally illustrating an exemplary computer system on which the present invention resides;
  • Figure 2 is a block diagram illustrating the functional layers of the network stack and the bypass path of the present invention
  • Figure 3 is a block diagram illustrating the functional layers of the NDIS path and the bypass path of the present invention.
  • Figure 4 is a ladder diagram illustrating the offload mechanism of the present invention.
  • Figures 5a-5d are diagrams illustrating an inverted tree of the present invention.
  • Figure 6 is a block diagram illustrating the synchronization between the host computer and the peripheral device
  • Figure 7 is a ladder diagram illustrating the upload mechanism of the present invention.
  • Figure 8 is a ladder diagram illustrating the offload mechanism of a secure protocol stack connection in accordance with the teachings of the present invention.
  • Figure 9 is a ladder diagram illustrating the upload mechanism of a secure offloaded protocol stack connection in accordance with the teachings of the present invention.
  • program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types.
  • program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types.
  • program modules may be practiced with other computer system configurations, including hand-held devices, multi-processor systems, microprocessor based or programmable consumer electronics, network PCs, minicomputers, mainframe computers, networked peripherals (e.g., networked printers) and the like.
  • the invention may also be practiced in distributed computing environments where tasks are performed by remote processing devices that are linked through a communications network.
  • program modules may be located in both local and remote memory storage devices.
  • FIG. 1 illustrates an example of a suitable computing system environment 100 on which the invention may be implemented
  • the computing system environment 100 is only one example of a suitable computing environment and is not intended to suggest any limitation as to the scope of use or functionality of the invention. Neither should the computing environment 100 be interpreted as having any dependency or requirement relating to any one or combination of components illustrated in the exemplary operating environment 100.
  • the invention is operational with numerous other general purpose or special purpose computing system environments or configurations.
  • Examples of well known computing systems, environments, and/or configurations that may be suitable for use with the invention include, but are not limited to, personal computers, server computers, hand-held or laptop devices, multiprocessor systems, microprocessor-based systems, set top boxes, programmable consumer electronics, network PCs, minicomputers, mainframe computers, networked peripherals (e.g., networked printers), distributed computing environments that include any of the above systems or devices, and the like.
  • the invention may be described in the general context of computer-executable instructions, such as program modules, being executed by a computer.
  • program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types.
  • the invention may also be practiced in distributed computing environments where tasks are performed by remote processing devices that are linked through a communications network.
  • program modules may be located in both local and remote computer storage media including memory storage devices.
  • an exemplary system for implementing the invention includes a general purpose computing device in the form of a computer 110.
  • Components of computer 110 may include, but are not limited to, a processing unit 120, a system memory 130, and a system bus 121 that couples various system components including the system memory to the processing unit 120.
  • the system bus 121 may be any of several types of bus structures including a memory bus or memory controller, a peripheral bus, a cross-bar, a switched bus fabric, and a local bus using any of a variety of bus architectures.
  • the system bus 121 may also be a hierarchy of buses.
  • such architectures include Industry Standard Architecture (ISA) bus, Micro Channel Architecture (MCA) bus, Enhanced ISA (EISA) bus, Video Electronics Standards Associate (VESA) local bus, No Cache NonUniform Memory Access (NC-NUMA) architecture bus, Cache-Coherent Non-Unifoim Memory Access (CC-NUMA) architecture bus and Peripheral Component Interconnect (PCI) bus also known as Mezzanine bus.
  • ISA Industry Standard Architecture
  • MCA Micro Channel Architecture
  • EISA Enhanced ISA
  • VESA Video Electronics Standards Associate
  • N-NUMA No Cache NonUniform Memory Access
  • CC-NUMA Cache-Coherent Non-Unifoim Memory Access
  • PCI Peripheral Component Interconnect
  • Computer 110 typically includes a variety of computer readable media.
  • Computer readable media can be any available media that can be accessed by computer 110 and includes both volatile and nonvolatile media, removable and non-removable media.
  • Computer readable media may comprise computer storage media and communication media.
  • Computer storage media includes both volatile and nonvolatile, removable and non-removable media implemented in airy method or technology for storage of information such as computer readable instructions, data structures, program modules or other data.
  • Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can be accessed by computer 110.
  • Communication media typically embodies computer readable instructions, data structures, program modules or other data in a modulated data signal such as a carrier wave or other transport mechanism and includes any information delivery media.
  • modulated data signal means a signal that has one or more of its characteristics set or changed in such a manner as to encode information in the signal.
  • communication media includes wired media such as a wired network or direct-wired connection, and wireless media such as acoustic, RF, infrared and other wireless media. Combinations of the any of the above should also be included within the scope of computer readable media.
  • the system memory 130 includes computer storage media in the form of volatile and/or nonvolatile memory such as read only memory (ROM) 131 and random access memory (RAM) 132.
  • ROM read only memory
  • RAM random access memory
  • BIOS basic input/output system
  • RAM 132 typically contains data and/or program modules that are immediately accessible to and/or presently being operated on by processing unit 120.
  • Figure 1 illustrates operating system 134, application programs 135, other program modules 136, and program data 137.
  • the computer 110 may also include other removable/non-removable, volatile/nonvolatile computer storage media.
  • Figure 1 illustrates a hard disk drive 141 that reads from or writes to non-removable, nonvolatile magnetic media, a magnetic disk drive 151 that reads from or writes to a removable, nonvolatile magnetic disk 152, and an optical disk drive 155 that reads from or writes to a removable, nonvolatile optical disk 156 such as a CD ROM or other optical media.
  • removable/non-removable, volatile/nonvolatile computer storage media that can be used in the exemplary operating environment include, but are not limited to, magnetic tape cassettes, flash memory cards, digital versatile disks, digital video tape, solid state RAM, solid state ROM, and the like.
  • the hard disk drive 141 is typically connected to the system bus 121 through a non-removable memory interface such as interface 140, and magnetic disk drive 151 and optical disk drive 155 are typically connected to the system bus 121 by a removable memory interface, such as interface 150.
  • hard disk drive 141 is illustrated as storing operating system 144, application programs 145, other program modules 146, and program data 147. Note that these components can either be the same as or different from operating system 134, application programs 135, other program modules 136, and program data 137. Operating system 144, application programs 145, other program modules 146, and program data 147 are given different numbers hereto illustrate that, at a minimum, they are different copies.
  • a user may enter commands and information into the computer 110 through input devices such as a keyboard 162 and pointing device 161, commonly referred to as a mouse, trackball or touch pad.
  • Other input devices may include a microphone, joystick, game pad, satellite dish, scanner, video input, or the like.
  • a user input interface 160 that is coupled to the system bus, but may be connected by other interface and bus structures, such as a parallel port, game port or a universal serial bus (USB).
  • USB universal serial bus
  • a monitor 191 or other type of display device is also connected to the system bus 121 via an interface, such as a video interface 190,
  • computers may also include other peripheral output devices such as speakers 197, printer 196, and a video output, which may be connected through an output peripheral interface 195.
  • the computer 110 may operate in a networked environment using logical connections to one or more remote computers, such as a remote computer 180.
  • the remote computer 180 may be another personal computer, a server, a router, a network peripheral device (e.g., a printer), a network PC, a peer device or other common network node, and typically includes many or all of the elements described above relative to the personal computer 110, although only a memory storage device 181 has been illustrated in Figure 1 .
  • the logical connections depicted in Figure 1 include a local area network (LAN) 171 and a wide area network (WAN) 173, but may also include other networks.
  • LAN local area network
  • WAN wide area network
  • Such networking environments are commonplace in offices, enterprise-wide computer networks, intranets and the Internet.
  • the personal computer 110 When used in a LAN networking environment, the personal computer 110 is connected to the LAN 171 through a network interface or adapter (e.g., a network interface card (NIC)) 170.
  • a network interface or adapter e.g., a network interface card (NIC)
  • the computer 110 When used in a WAN networking environment, the computer 110 typically includes a modem 172 or other means for establishing communications over the WAN 173, such as the Internet.
  • the modem 172 which may be internal or external, may be connected to the system bus 121 via the user input interface 160, or other appropriate mechanism.
  • program modules depicted relative to the personal computer 110, or portions thereof, may be stored in the remote memory storage device.
  • Figure 1 illustrates remote application programs 185 as residing on memory device 181. It will be appreciated that the network connections shown are exemplary and other means of establishing a communications link between the computers may be used.
  • Figure 2 illustrates the interrelationship of some of the components that make up a networking model and the components of the present invention.
  • networked messages are sent by the application 200 through network stack 202 to the peripheral device 204 where the messages are sent to other devices and applications on the network and received from the other devices and applications.
  • the network stack 202 includes one or more intermediate software layers 206. Data sent from application 200 travels through the intermediate software layer(s) 206 where specific operations may be performed on the data such as packaging the data, reliable data transmission, data encryption and calculation of a message digest
  • the switch 208 is used to offload the processing unit 120 from performing network stack operations for the intermediate software layer(s) 206. While the switch 208 is shown separately, it should be noted that the switch 208 may be integrated into the top intermediate layer of the network stack 202. Data is sent to the peripheral device 204 via chimney 210 for the peripheral device 204 to perform network stack operations. In this hierarchy, the intermediate software layers do not have to exclusively reside in the host or the peripheral device and it allows any of the intermediate layers to either be completely offloaded, to remain in the host, or a combination of both (e.g., offload one or more specific connections). Additionally, chimneys may be layered on top of chimneys (e.g., an IPSEC chimney may be layered on top of a TCP chimney).
  • a connection may be any combination of reliable and unreliable data transfer and unicast or multicast data transfer.
  • the host updates cached variables (as described below) in the peripheral device 204. For example, a transport control block (TCB) state entry for a connection can be offloaded for the transport layer with a route cache entry (RCE) for the network layer offloaded to the peripheral device 204.
  • the switch 208 continues to send traffic for a different TCB through the network stack 202 that shares the same RCE while the switch 208 sends frame through the chimney 210 for the offloaded TCB.
  • the switch 208 initiates the offload by sending the intermediate layer 206 an offload request
  • the offload request includes resource information that helps the peripheral device 204 decide whether it can successfully offload the connection.
  • Each intermediate layer 206 either refuses the offload request or adds resource information to the offload request and sends the offload request to the adjacent software layer in the network stack 202.
  • the peripheral device 204 calculates whether it has resources available to offload the connection.
  • the peripheral device 204 refuses the offload request if the offload is not possible. Otherwise, the peripheral device 204 accepts the offload request and allocates resources for the connection.
  • the peripheral device 204 completes the offload request by sending a completion message having a linked list of parameters to the intermediate software layer(s) 206.
  • the linked list of parameters provides information to the intermediate software layer(s) 206 and switch 208 to allow the intermediate software layer(s) 206 and switch 208 to communicate with the peripheral device.
  • Each intermediate software layer 206 removes information for its layer from the linked list of parameters
  • Each state may have three types of variables: CONST, CACHED, and DELEGATED.
  • a state may have all three types of variables or a subset of the three types of variables.
  • CONST variables are constants that never change during the life of the offloaded connection. They are not read back to the layers when the connection is uploaded.
  • the host processing unit 120 maintains ownership of CACHED variables and ensures that any changes to a CACHED variable in the host processing unit 120 are updated in the peripheral device 204. Control messages that change the CACHED state are handled by the network stack 202. As a result, the host will write but does not need to read back the CACHED variables when the connection is uploaded.
  • the host processing unit 120 transfers ownership of DELEGATED variables to the peripheral device 204.
  • the DELEGATED variables are written once when the offload occurs and are read back when the offload is terminated. By only transferring back the DELEGATED variables, the overhead of transferring the connection back to the host is minimized.
  • State that must be shared (e.g. controlled) between the network stack 202 and the peripheral device 204 that for various performance reasons is being offloaded (i.e., delegated) is cleanly divided between the network stack 202 and chimney 210 (e.g., IP ID in TCP offloads) such that both the network stack 202 and peripheral device 204 each owns an exclusive portion of the state.
  • the host processing unit 120 queries the peripheral device 204 for DELEGATED variables when needed (e.g., for statistics).
  • the host processing unit 120 may also query CONST or CACHED variables for diagnostics. Dividing the state into three categories enables the network stack 202 to coexist cleanly with the chimney 210. It should be noted that the state may be included in the offload request This can be done if either the state does not contain delegated state variables or contains delegated state variables that will not change between the initial offload request and the completion of the offload request
  • the peripheral device 204 or the host decides when an offloaded connection is to be uploaded.
  • the upload is initiated by either the peripheral device 204 or the switch 208.
  • the peripheral device 204 completes all outstanding requests with appropriate state and hands the delegated state of the topmost intermediate layer to the switch 208.
  • the switch 208 queues any further transmit requests and stops posting receive buffers.
  • the switch 208 commands the topmost intermediate layer to take control of the delegated state.
  • the topmost intermediate layer takes control of the delegated state and sends a completion message to the switch 208.
  • the switch 208 confirms the upload to the peripheral device 204, which enables the peripheral device 204 to free resources that are no longer being used.
  • the topmost intermediate layer forwards incoming data packets for the offloaded connection to the peripheral device 204 for processing until it takes control of the delegated state.
  • Data packets may arrive between the time the peripheral device 204 hands the delegated state to the switch 208 and the time that the topmost intermediate layer takes control of the delegated state. After the peripheral device 204 hands the delegated state to the switch 208, it can no longer process incoming data packets.
  • the peripheral device 204 sends an error message to the topmost intermediate layer indicating an upload is in progress when it receives incoming data.
  • the error message informs the topmost intermediate layer to stop forwarding incoming data and to buffer further data until the topmost intermediate layer receives the delegated state.
  • the incoming data could be forwarded to the peripheral device 204 for the peripheral device 204 to buffer the data.
  • Multiple connections may be off-loaded by an intermediate software layer 206 to the peripheral device 204.
  • a reference counter is maintained by the intermediate software layer 206 of the number of upper layer state objects (i.e., state objects of layers above the intermediate software layer 206) which reference the intermediate software layer's state object for offload.
  • a state object as used herein is a collection of state variables for a particular layer that are categorized as CONST, CACHED, or DELEGATED as used herein. If an intermediate layer's offloaded state object has no references to it by a layer above it, the intermediate layer 206 sends a message to the peripheral device 204 to upload the state object for the intermediate layer and send delegated state variables to the intermediate layer 206. The peripheral device 204 deletes the state object for the intermediate layer 206 and the intermediate layer 206 sends a completion message to the switch 208.
  • the peripheral device 204 is NIC 170
  • the switch 208 is a transport layer interface switch (TLI) 306
  • the network stack 202 comprises a transport layer 300, a network layer 302, and a framing layer 304.
  • Network layer 302 is also known as a path layer and the framing layer 304 is also known as a neighbor layer.
  • Networked messages are sent by the application 200 through network stack 202 to the NIC 170 during operation.
  • Data sent from the application 200 travels through the TLI switch 306, which controls whether the data goes down the host based network stack 202 or the chimney 308.
  • the TLI switch 306 may be incorporated into the top layer of the network stack 202.
  • the software layers in the network stack 202 receive data from the application 200, package it in a packet form and sends it to the peripheral device hardware 314 via NDIS minidriver 310.
  • Other tasks the network stack 202 may perform as a data packet passes through the stack 202 includes data encryption, reliable data transmission, and calculation of a message digest (e.g., checksum or CRC for the data packet). Many of these tasks are performed by the processing unit 120 and are processor intensive.
  • the TL1 switch 306 is used to offload the processing unit 120 from performing stack operations by sending data for connections to the NIC 170 via chimney 308 (and chimney driver 312).
  • NDIS minidriver 310 and chimney driver 312 is the NDIS API in Microsoft? operating systems.
  • TCP transmission control protocol
  • SCTP stream control transmission protocol
  • UDP user datagram protocol
  • the invention may also be used to offload higher function protocols such as the internet small computer system interface (iSCSI), the network file system (NFS), or the common interface file system (CIFS).
  • a system administrator could select a specific service to be offloaded.
  • a specific connection may be offloaded if traffic (in terms of number of bytes or packets) on the connection is consuming a significant amount of resources.
  • Types of services may be offloaded.
  • security protocols such as IPSEC may be offloaded.
  • Offloads may be driven by policy. For example, an administrator may have a policy that all connections from within an organization are offloaded first.
  • System resources e.g., cpu utilization, data cache use, page table cache use, memory bandwidth
  • Figure 4 illustrates the steps taken to offload a TCP connection.
  • a three stage process is used. In general, the three stage process is to allocate resources required to offload the TCP connection, provide handles to each of the layers 300, 302, 304, 306 and offloads the state for each of the layers 300, 302, 304, 306 to the NIC 170.
  • the TLI switch 306 buffers all messages sent from the application 200.
  • the transport layer 300 buffers the data.
  • the offload is complete, the buffered data is transferred to the NIC 170 using the same mechanism as offload data transmission.
  • the NIC 170 continues to move the data up through the layers 300, 302, 304, 306 until the transport layer delegated state is handed to the NIC 170.
  • the TLI switch 306 initiates the offload by sending the transport layer 300 an offload request (line 400).
  • the offload request includes a pointer to the next layer's local state (e.g., a TCB pointer for transport layer 300, an RCE pointer for network layer 302, an ARP table pointer for the framing layer 304 or a NDIS miniport pointer for the NDIS minidriver 310), the offload type (e.g., TCP for TLI switch 306, IPv6 for network layer 302, etc.), and resource information that helps the NIC 170 decide whether it can successfully offload the TCP connection.
  • the TLI switch 306 may also provide dispatch tables to the NIC 170.
  • the transport layer 300 either refuses the offload request or sends an offload request to network layer 302 with TCP resource information added to the TLI switch resource information (line 402).
  • the network layer 302 receives the offload request and either refuses to offload the connection or sends an offload request to the framing layer 304 with network resource requirements added to the TCP resource information and the TLI switch resource information (line 404).
  • the network layer 302 may also provide dispatch tables to the NIC 170.
  • the framing layer 304 either refuses to offload the connection or sends an offload request to the NIC 170 with framing resource requirements added to the network resource requirements, the TCP resource information and the TLI switch resource information (line 306).
  • the NIC 170 receives the offload request and calculates whether it has resources available to offload the TCP connection. If the NIC decides the offload is not possible, it refuses the offload request. If the NIC decides the offload is possible, it accepts the offload request and allocates resources (e.g., TCB, route cache entry (RCE), address resolution protocol (ARP) table entry (ATE)) for the connection.
  • resources e.g., TCB, route cache entry (RCE), address resolution protocol (ARP) table entry (ATE)
  • the NIC 170 creates a linked list of parameters and dispatch tables to hand to the layers 300, 302, 304 and 306 and completes the offload request by sending a completion message having the linked list of parameters to the framing layer 304 (line 408).
  • the parameters include an offload handle and dispatch table for each of the layers 300, 302, 304, 306.
  • an offload handle means a mechanism to allow a software layer to communicate with the peripheral device.
  • the offload handle may be a pointer-based handle, an integer value used as a lookup into an array, a hash table (e.g., a hashing function), a communication channel between the software layer (or network stack) and the peripheral device, or a set of parameters passed down by a software layer that the peripheral device uses to look up the state object.
  • the dispatch tables are used to send data directly to the NIC 170 or receive data directly from the NIC 170.
  • the dispatch tables can also be used to provide diagnostics. For example, a software layer could be added to monitor the system and inject faults to make sure the system is functioning properly.
  • the dispatch table can be patched by software layers that can add additional functionality if needed. For example, a software layer could be added to provide the functionality of a filter driver. Patching is typically done by grabbing the pointer to the original function where the added function is being inserted and redirecting it (i.e., pointing it) to the added function. After the patch has been inserted, the added function performs its function and then calls the original function whenever the original function is called
  • the framing layer 304 stores the offload handle and dispatch table for the framing layer in its ARP Table Entry for easy updates if the destination MAC address changes or the encapsulation type changes.
  • the framing layer 304 then updates the NIC 170 state associated with the ATE (line 410).
  • the framing layer 304 removes its state from the linked list and forwards the remaining information in the linked list to the network layer 302 (line 412).
  • the network layer 302 stores the offload handle and dispatch table for the network layer 302.
  • the network layer 302 also sends it state to the NIC 170 (line 414).
  • the network layer 302 removes network layer information from the linked list and sends a completion message having the linked list of parameters and dispatch tables to the transport layer 300 (line 416).
  • the network layer 302 may forward IP fragments it receives for the offloaded state to the NIC 170 for processing or it may process the IP fragments in the network layer and forward them to the transport layer 300.
  • the layer's state object is sent with the offload request
  • the framing layer state object and network layer state object is sent with the offload request and only if the cached state changes between the offload request and the completion event is the state updated.
  • the entire layer state object can only be sent with the offload request if the delegated state is either not present or cannot change between the offload request and the completion of the offload request.
  • state variables classified as CONST may be sent with the offload request even if the delegated state is present and may change between the offload request and the completion of the offload request.
  • the transport layer 300 stores the offload handle for the transport layer and sends its state to the NIC 170 (line 418). If there are any outstanding send or receive buffers pending, the transport layer 300 returns the buffers to the TLI switch 306. Once the transport layer 300 starts handing the buffers back to the TLI switch 306, the TLI switch 306 will stop sending buffers to the transport layer 300 and queues them and waits for the transport layer 300 to send a completion message having the linked list of parameters and the dispatch table to the TLI switch 204. The transport layer 300 returns all buffers and then sends the completion message (line 420). Once the TLI switch 306 receives the completion message, the TLI switch 306 transfers the send and receive buffers to the NIC 170 (line 422).
  • the TLI switch 306 uses the dispatch table to post all outstanding and future receive buffers and sends to the NIC 170 for processing. During the time the offload request takes to complete, each layer 300, 302, 304 either refuses new offload requests for the offloaded state object (i.e., the state object associated with a layer) or queues them until the offload is complete.
  • the offloaded state object i.e., the state object associated with a layer
  • the transport layer 300 still has the ability to process incoming TCB data and hand the data to the TLI switch 306 if the transport state hasn't been offloaded to the NIC 170. If TCB data arrives in the middle of an offload, the transport layer 300 may either hold on to the data or process the data and hand it to the TLI switch 306. Between the time that the transport layer 300 sends its state to the NIC 170 (line 418) and the time the TLI switch transfers buffers to the NIC 170 (line 422), incoming TCB data coming up through the network stack 202 is sent to the NIC 170.
  • the network layer 302 and the framing layer 304 pass the offload handles they received from the NIC 170 from the prior offload to the NIC 170. This signals the NIC 170 that resources for the network layer 302 and framing layer 304 have already been allocated, which conserves NIC resources and speeds up the offload.
  • the layers 300, 302, 304 pass their state to the NIC 170.
  • Each state has three types of variables: CONST, CACHED, and DELEGATED.
  • CONST variables are constants that never change during the life of the offloaded connection. They are not read back to the layers when the connection is terminated.
  • the host processing unit 120 maintains ownership of CACHED variables and ensures that any changes to a CACHED variable in the host processing unit 120 are updated in the NIC 170. As a result, the host will write but never read back the CACHED variables (unless system diagnostics requests it).
  • the host processing unit 120 transfers ownership of DELEGATED variables to the NIC 170.
  • the DELEGATED variables are written once when the offload occurs and are read back when the offload is terminated. By only transferring back the DELEGATED variables, the overhead of transferring the connection back to the host is minimized
  • the host processing unit 120 queries the NIC 170 for DELEGATED variables when needed (e.g., for statistics)
  • the CONST variables for the transport layer 300 include the destination port, the source port, a flag to indicate there is a Mobile IP case where the 'care-of' address can change, SEND and RECV window scale factors, and the NIC handle for the network layer 302.
  • the CACHED variables for the transport layer 300 are TCP variables and IP variables.
  • the TCP variables include the Effective MSS, the number of bytes to be copied in the receive indicate by the NIC 170, a flag to turn off Nagling, a flag to indicate that Keep-Alive is needed, and Keep-Alive settings (i.e., interval, number of probes, and delta).
  • the IP variables include TOS and TTL.
  • the DELEGATED variables include current TCP state, sequence number for next RECV (i.e., RCV.NEXT), receive window size (RCV.WND), the sequence number for First Un-Acked Data (SND.UNA), the sequence number for next SEND (SND.NEXT), the maximum sequence number ever sent (SND.MAX), the maximum Send Window (MAX_WIN), the current congestion window (CWIN), the slow start threshold (SSTHRESH), the smoothed RTT (8*A), Delta (8*D), the current retransmit count, the time remaining for Next Retransmit, and the time stamp to be echoed.
  • the CONST variables for the network layer 302 include the destination IP address (for either IPv4 or 1Pv6) and the source destination IP address (for either IPv4 or IPv6).
  • the CACHED variables for the network layer 302 include the N1C handle for the framing layer 304.
  • the DELEGATED variables for the network layer 302 include the IP Packet ID start value.
  • the CACHED variables for the framing layer 304 include the ARP address and a flag to indicate the format of the header (e.g., LLC/SNAP [Logical Link Control/Sub-Network Access Protocol]or DIX [Digital, Intel, Xerox]).
  • the transport layer state includes a handle for the network layer and the network layer state includes a handle for the framing state because the network layer state can be shared between multiple connections and the framing layer state can be shared between multiple paths (e.g., IP aliases).
  • This hierarchy is maintained for several reasons.
  • a connection requires a NIC handle for the network layer because the IP ID namespace must be managed across all offloaded connections on a per path basis.
  • a path requires a NIC handle for the framing layer because a route update could change the next hop address, thus pointing to a new MAC address.
  • the hierarchy also condenses the amount of state required to be maintained by the NIC.
  • an ARP update for IPv4 could change the mapping from an IP address to a MAC address (e.g., an interface failed over on the server).
  • the host maintains the MAC address as a cached variable, thus it only needs to do a single update of the cached state and all connections are failed over to the new interface.
  • the NIC 170 is responsible for assigning packet identifiers (e.g., IP IDs) for the packets it sends. IP ID is offloaded on either a per interface basis or a per layer state object basis. The NIC 170 is assigned a portion of the IP ID namespace. In one embodiment, the NIC 170 is assigned half of the total IP ID namespace and is given an IP packet ID start value to use when the network state is passed to the NIC 170.
  • packet identifiers e.g., IP IDs
  • the NIC 170 transfers the next IPID value it would use to the network layer to store for the next offload that occurs and the host processing unit 120 continues to use the portion of the IP ID namespace it was assigned.
  • the host processing unit 120 could use the full IP ID name space, but the counter would have to be set each time an offload occurs.
  • the NIC 170 places data into receive buffers in the order the data is received and fills application buffers in the order they are posted for the offloaded connection. Many applications wait for a receive indication before posting a receive buffer.
  • the NIC 170 has a global pool of buffers to use if data arrives for a connection and no application receive buffers have been posted.
  • the global pool of buffers is used across the offloaded connections and may be used to implement: 1) handling of out-of order TCP transmissions; 2) de- fragmenting IP datagrams; 3) a buffer copy algorithm rather than a zero copy algorithm if the application is posting buffers that are too small for a zero copy algorithm.
  • a per-connection pool of buffers may be used if efficient use of resources is not a concern.
  • the global pool of buffers is used if a NIC does not support a per connection pool of buffers or for lack of system resources (e.g., not enough resources to pin the application buffer in memory).
  • the NIC 170 has an inverted tree 500 that is representative of the offload once an offload has occurred, In the figures, dotted lines represent new states allocated by the NIC 170.
  • the NIC 170 has an ARP entry 502 coupled to a route cache entry 504 that is coupled to a TCP entry 506. If, for example, all traffic is going to a router, the next hop will always be to the same ARP entry 502. If the route cache entry 504 is to be used for the next TCP connection offload, the only new resource is the new offloaded TCB.
  • the intermediate software layers that have already offloaded their state (e.g.
  • the network layer 302 and framing layer 304) would simply insert the NIC generated offload handle that was allocated on the previous offload request.
  • the NIC 170 only has to allocate new resources (e.g. TCP entry 508) and send offload handles for the new resources back up the network stack 202.
  • the inverted tree 500 now has TCP entry 508 coupled to the route cache entry 504 (see figure 5b ). This approach saves NIC resources and speeds up the offload. Additionally, if a cached variable state changes, only a single structure needs to be updated. If all state for the various software layers in the chimney were offloaded as a single entry, any state update below the top software layer would require multiple updates.
  • Figure 5C shows the inverted tree 500 with a more complex configuration.
  • TCP connections 506 and 508 utilize route cache entry 504.
  • TCP connections 512 and 514 reference route cache entry 510. If any ARP update occurs (e.g., a multi-homed server's interface fails over), only entry 502 must be updated. This enables potentially thousands or hundreds of thousands of connections to be failed-over to a new interface with only a single update to the NIC 170 required.
  • Figure 5d shows two independent inverted trees (entries 502-508 and entries 510-516) merged into a single inverted tree 500 after a route update occurs.
  • next hop ARP entry for route cache entry 510 is ARP table entry 516.
  • the next hop ARP table entry is ARP table entry 502.
  • the cached state variables synchronize the two paths with the processing unit 120 updating the cached state variables in the NIC 170 as previously indicated.
  • the updating of cached variables is indicated by arrows 602, 604, 606.
  • the NIC 170 determines whether the incoming data packet goes through the offloaded path or the non-offloaded path (i.e., through the NDIS path of NDIS minidriver 310 and the layers 304, 302, 300). In one embodiment, the NIC 170 determines which path to send the incoming data packet by performing a hashing function on the source and destination TCP port number, source and destination IP address and protocol type. If the hash matches the offloaded connection parameters (i.e., a hash bucket chain is walked and exact matching of all the tuples of the connection occurs), the chimney 608 is used. If the hash does not match the hash index, the non-offloaded path through network stack 202 is used. Control messages which update cached states are handled by the host. This results in the NIC 170 not having to handle any control messages outside of the offloaded connection such as ICMP, DNS, and RIP messages.
  • the present invention provides a user with the capability to derive statistics using existing tools such as Netstat to retrieve a variety of information including all connections on the host, connection parameters such as protocol type, local and remote port and IP address bindings, state of the connection, process id, etc.
  • Statistics are gathered on either a per layer basis or a per layer state object basis in the present invention
  • the layer state objects may be grouped to gather statistics across multiple layer state objects. For example, statistics for the network layer may be split such that the statistics are for each protocol being used (e.g., IPv4 and IPv6).
  • Statistics associated with CONST and CACHED state variables are provided by the host and statistics associated with DELEGATED state variables are provided by the peripheral device 204. When a query is made, the statistics associated with DELEGATED state variables are appended to the statistics associated with CONST and CACHED state variables.
  • the statistics for a TCB are the combination of statistics tracked by the host and the statistics tracked by the peripheral device.
  • the statistic for packet count is the sum of the host layer state statistic and the peripheral device layer state statistic.
  • TCP MIB Management Information Base
  • IPv4 MIB statistics is presented in Table 2 below.
  • the first column is the field
  • the second column designates if the peripheral device or the host network stack is responsible for tracking the statistic
  • the third field indicates how the field is tracked.
  • Statistics that the peripheral device is responsible for are tracked on a per layer state object basis or a per layer basis.
  • Per layer as used herein means the statistic is tracked per layer per peripheral device per protocol. Note, however, that when the statistic is synthesized from the host state and the state from the peripheral device(s), it is generally presented on a per protocol basis.
  • Adapter statistics are queried through the regular NDIS interface.
  • the adapter statistics includes variables such as bytes sent, bytes received, etc.
  • the ts_RtoAlgoithm is a value for an algorithm used to determine the timeout value used for retransmitting unacknowledged octets.
  • the ts_Rto_Min is a value for the minimum value permitted by a TCP implementation for the retransmission timeout measured in milliseconds.
  • the ts_Rto_Min is the maximum value permitted by a TCP implementation for the retransmission timeout measured in milliseconds.
  • the ts_MaxConn is the total number of TCP connections that can be supported
  • the ts_ActiveOpens is the number of times TCP connections have made a direct transition to the SYN_SENT state from the CLOSED state.
  • the ts_PassiveOpens is the number of times TCP connections have made a direct transition to the SYN_RCVD state from the LISTEN state.
  • the ts_AttemptFails is the number of times TCP connections have made a direct transition to the CLOSED state from either the SYN-SENT state or the SYN-RCVD state plus the number of times TCP connections have made a direct transition to the LISTEN state from the SYN-RCVD state.
  • the ts_EstabResets is the number of times TCP connections have made a direct transition to the CLOSED state from either the ESTABLISHED state or the CLOSE- WAIT state.
  • the ts_CurrEstab is the number of TCP connections for which the current state is either ESTABLISHED or CLOSE- WAIT.
  • the ts_InSegs is the total number of segments received, including those received in error.
  • the ts_OutSegs is the total number of segments sent, including those on current connections but excluding those containing only retransmitted octets.
  • the ts_RetransSegs is the total number of segments retransmitted.
  • the ts_InErrs is the total number of segments received in error (e.g., bad TCP checksums).
  • the ts_OutRsts is the number of TCP segments sent containing the RST flag.
  • the ts_NumCons is the total number of TCP connections that currently exist. Table 2. IPv4 MIB Statistics Split IPSNMPInfo Structure field Responsibility How field is tracked ipsi_Forwarding host network stack Done by stack only ipsi_DefaultTTL host network stack Stack has complete info ipsi_InReceives host network stack and peripheral device Per layer ipsi_InHdrErrors host network stack and peripheral device Per layer ipsi_InAddrErrors host network stack Done by stack only ipsi_Forwdatagrams host network stack Done by stack only ipsi_UnknownProtos host network stack Done by stack only ipsi_InDiscards host network stack and peripheral device Per layer ipsi_InDelivers host network stack and peripheral device Per layer ipsi_OutRequests host network stack and peripheral device Per layer ipsi_RoutingDiscards host network stack Done by stack only ipsi_OutDiscards host network stack and peripheral device Per layer ipsi_OutNooutes host network stack
  • the ipsi_Forwarding is a value that provides an indication of whether the host is acting as an IP router in respect to the forwarding of datagrams received by, but not addressed to, the host.
  • the ipsi_DefaultTTL is the default value inserted into the Time-To-Live field of the IP header of datagrams originated at this entity, whenever a TTL value is not supplied by the transport layer protocol.
  • the ipsi_InReceives is the total number of input datagrams received from interfaces, including those received in error.
  • the ipsi_InHdrErrors is the number of input datagrams discarded due to errors in their IP headers, including bad checksums, version number mismatch, other format errors, time-to-live exceeded, errors discovered in processing their IP options, etc.
  • the ipsi_InAddrErrors is the number of input datagrams discarded because the IP address in their IP header's destination field was not a valid address to be received at the host.
  • the ipsi_ForwDatagrams is the number of input datagrams for which the host was not their final IP destination, as a result of which an attempt was made to find a route to forward them to that final destination.
  • the ipsi_UnknownProtos is the number of locally-addressed datagrams received successfully but discarded because of an unknown or unsupported protocol.
  • the ipsi_InDiscards is the number of input IP datagrams for which no problems were encountered to prevent their continued processing, but which were discarded (e.g., for lack of buffer space).
  • the ipsi_InDelivers is the total number of input datagrams successfully delivered to IP user-protocols.
  • the ipsi_OutRequests is the total number of IP datagrams which local IP user- protocols (including ICMP) supplied to IP in requests for transmission.
  • the ipsi_RoutingDiscards is the number of routing entries which were chosen to be discarded even though they are valid.
  • the ipsi_OutDiscards is the number of output IP datagrams for which no problem was encountered to prevent their transmission to their destination, but which were discarded (e.g., for lack of buffer space).
  • the ipsi_OutNoRoutes is the number of IP datagrams discarded because no route could be found to transmit them to their destination.
  • the ipsi_ReasmTimeout is the maximum number of seconds which received fragments are held while they are awaiting reassembly at the host.
  • the ipsi_ReasmReqds is the number of IP fragments received which needed to be reassembled at the host.
  • the ipsi_ReasmOKs is the number of IP datagrams successfully re-assembled
  • the ipsi_ReasmFails is the number of failures detected by the IP re-assembly algorithm (e.g., timed out, errors, etc).
  • the ipsi_FragOKs is the number of IP datagrams that have been successfully fragmented at the host.
  • the ipsi_FragFails is the number of IP datagrams that have been discarded because they needed to be fragmented at the host but could not be, e.g., because their Don't Fragment flag was set
  • the ipsi_FragCreates is the number of IP datagram fragments that have been generated as a result of fragmentation at the host
  • the ipsi_Numlf is the total number ofuseable interfaces.
  • the ipsi_NumAddr is the total number of unique IP addresses on the system.
  • the ipsi_NumRoutes is the total number of currently active routes.
  • the present invention also provides a method to upload an offloaded network connection from the peripheral device to the host
  • an upload occurs.
  • the route may have changed, requiring traffic to be sent on a different interface.
  • Connection traffic behavior may change such that it is no longer be suitable for offload For example, there may be insufficient traffic, lack of activity, or the connection is being flow controlled for longer than a set time (e.g., no window updates are being received).
  • the peripheral device may not be able to support a particular function, the traffic behavior may be unsuitable for offload if there are too many IP fragments, too much out-of-order traffic, use of out-of-band data, too many retransmissions, a keep-alive has timed out, a security association becomes invalid and is not renewed, or too much data is being forwarded to the peripheral device.
  • Other reasons for uploading an offloaded connection are due to resource issues. For example, the peripheral device may lack resources to continue processing the connections). Another connection may have higher priority than the offloaded connection and uploading a connection when peripheral device resource availability is below a threshold may enable the higher priority connection to continue to use peripheral device resources.
  • System resources may have changed such that the host processor has resources to handle an offloaded connection.
  • the chimney may require different resources than the original offload (e.g., security filter change, etc.).
  • the host can determine if the peripheral device's resources are approaching threshold levels where an offload connection would be more efficiently handled by the host processing unit.
  • the thresholds may include traffic size (number of bytes or packets), number of fragments, window size, and type of offload.
  • the upload is initiated by either the peripheral device 204 (e.g., the NIC 170) or the TLI switch 306.
  • the connection may be uploaded for a variety of reasons. The reasons include the connection moving to another peripheral device, a media disconnect occurring, too many out of order segments, too much data is being forwarded to the peripheral device 204, the application 200 is not pre-posting buffers, too many IP fragments, a low bandwidth connection, and too many retransmissions.
  • FIG. 7 shows the upload being initiated by the TLI switch 306 (line 700). Note that if the NIC 170 initiates the upload, line 700 would not be present. Once the upload is initiated, the NIC 170 completes all outstanding requests with appropriate state and hands the delegated transport layer state to the switch layer (line 702). The NIC 170 might not complete a transmission or completely fill a receive buffer. The NIC 170 just ensures that all transmit and receive state is synchronized with the delegated state handed back to the transport layer 300. The TLI switch 306 queues any further transmit requests and stops posting receive buffers. The TLI switch 306 commands the transport layer to take control of the delegated transport state (line 704).
  • the transport layer 300 stops forwarding any segments it receives to the NIC 170 and takes control of the delegated state and sends a completion message to the TLI switch 306 (line 706)
  • the TLI switch 306 confirms the upload to the NIC 170 (line 708), which enables the NIC 170 to free resources.
  • the transport layer 300 also informs the network layer 302 of the uploading connection before or after the completion message is sent to the TLI switch 306 (line 710).
  • the transport layer 300 forwards incoming data packets for the offloaded connection to the NIC 170 for processing until it takes control of the delegated state (line 706).
  • Data packets may arrive between the time the NIC 170 hands the delegated state to the TLI switch 306 (line 702) and the time that the transport layer 300 takes control of the delegated state (line 706).
  • the NIC 170 hands the delegated state to the TLI switch 306, it can no longer process incoming data packets.
  • the NIC 170 sends an error message to the transport layer 300 indicating an upload is in progress and may discard the incoming packet.
  • the error message informs the transport layer 300 to stop forwarding incoming data.
  • the transport layer 300 buffers further data until it receives the delegated state.
  • Multiple connections may be offloaded by intermediate software layers to the peripheral device.
  • a reference counter is maintained by the intermediate software layer of the number of connections offloaded from the intermediate software layer to the peripheral device. If the reference count goes to zero, an upload request is generated to the next intermediate software layer. This will cause the next layer's reference count to be decremented.
  • the upload request continues down the network stack 202 if the next layer's reference count goes to zero. This process repeats until either an intermediate software layer's reference count is not zeroed or the peripheral device receives the upload request
  • the network layer 302 decrements a reference count of the number of offloaded state objects associated with the NIC 170. If the reference count goes to zero, then no TCBs are using the resources allocated in the NIC 170 for the network layer 302.
  • the network layer 302 sends a message to the NIC 170 to upload the state object for the network layer 302 and send delegated network state variables to the network layer 302 (line 712).
  • the NIC 170 deletes the state and sends delegated network state variables and the next IPID value the NIC 170 would have used to the network layer 302 (line 714).
  • the network layer 302 stores this information to use as the initial value if a connection is offloaded again.
  • the network layer 302 also sends a message to the framing layer 304 to cause the framing layer 304 to decrement its reference count (line 716).
  • the framing layer 304 also maintains a reference count and decrements its reference count when the message from the network layer 302 is received. If the reference count in the framing layer 304 goes to zero, the framing layer sends a message to the NIC 170 to delete the framing layer state (line 718). The NIC 170 deletes the state variables in the NIC 170 and sends any delegated state variables it has to the framing layer (line 720). The framing layer 304 sends a completion message to the network layer 302 (line 722) and the network layer 302 sends a completion message to the transport layer (line 724).
  • a TCP connection may be required to use a secure connection using security protocols such as IPSEC at any point in its lifetime. If a connection is IP secure and the peripheral device 204 can not handle security, the connection cannot be offloaded. When a secure IP connection is offloaded, the security association(s) state is divided into CONST, CACHED, and DELEGATED variables and are handled as previously described.
  • the host processing unit 120 manages control messages such as renegotiation of keys.
  • the peripheral device 204 performs all necessary IPSEC data operations using the security association state variables.
  • An IPSEC layer offload begins when the transport layer 300 sends an offload request to IPSEC layer 800 with TCP resource information added to the TL1 switch resource information (line 402').
  • the IPSEC layer 800 sends an offload request to the network layer 302 with IPSEC resource requirements added to the TCP resource information and the TLI switch resource information (line 802).
  • the resource requirements include the number of security associations the IPSEC layer wants to offload. If the NIC accepts the offload request, it allocates resources to handle the security associations.
  • the network layer 302 sends a completion message having the linked list of parameters and the dispatch table to the IPSEC layer instead of the transport layer 300 (line 804).
  • the IPSEC layer 800 When the IPSEC layer 800 receives the completion message, it sends the IPSEC layer states to the NIC 170 as part of inbound descriptors and outbound descriptors if the state has not been previously offloaded and transfers ownership of the delegated state in the security association to the NIC 170 (line 806). If the state has been previously offloaded, the IPSEC layer increments a reference count. Once the ownership has been transferred, the NIC 170 decrypts and encrypts all packets. The IPSEC layer 700 sends a completion message having the linked list of parameters and the dispatch table to the transport layer (line 414').
  • the CONST state variables passed to the NIC 170 from the IPSEC layer 800 consist of information required to classify packets to a particular security association and information specific to inbound and outbound security associations.
  • the CONST variables include source and destination port, protocol type, and security association variables.
  • the CACHED state variables comprise factors for deciding the life time of the security association and information specific to inbound and outbound security associations.
  • the CACHED variables include a soft limit (e.g., a rekey on byte count) and a hard limit (e.g., a stop on byte count) based on the bytes encrypted, a soft limit (e.g., rekey at a predefined tick) and a hard limit (e.g., stop at a predefined tick) on the maximum time the security association can be used, and a hard limit (e.g., maximum idle ticks) on the maximum idle time for which a security association may be used.
  • the NIC 170 abides by the soft and hard limits. When a soft limit is reached, the NIC 170 informs the host processing unit 120. When a hard limit is reached, the NIC 170 discards the security association.
  • the DELEGATED variables comprise running information and information specific to inbound and outbound security associations.
  • the DELEGATED variables include a count of the bytes encrypted or decrypted with the security association, the life time of the security association, and the idle time of the security association.
  • the transport layer 300 informs the IPSEC layer 800 of the uploading connection before or after the completion message is sent to the switch layer 306 (line 710').
  • the reference count associated with all security associations is decremented. If no reference count goes to zero, the IPSEC layer 800 sends a completion message to the transport layer 300 (line 724'). If the connection being offloaded is the last connection using a specific security association, the IPSEC layer 800 sends a message to the NIC 170 to upload the delegated state variables to the IPSEC layer 800 (line 900).
  • the NIC 170 returns the delegated state variables to the IPSEC layer 800 (line 902).
  • the NIC 170 stops using the security association and sends packets that belong to the security association to the IPSEC layer 800 through the stack 202.
  • the IPSEC layer 800 sends a completion message to the NIC 170 and the NIC 170 frees the resources allocated for the security association (line 904).
  • the IPSEC layer 800 also sends a message to the network layer 302 informing the network layer 302 of the uploaded state (line 906).
  • the framing layer 304 sends a completion message to the network layer 302 (line 722)
  • the network layer 302 sends a completion message to the IPSEC layer (line 908)
  • the IPSEC layer 800 sends a completion message to the transport layer (line 724').
  • an update e.g., ARP update or RIP update
  • the local state is simply updated and a flag is set to indicate that the state has changed if the state object was sent with the offload request.
  • the first possible solution is to have the completion message always perform the second update, which can result in recursion problems if a large number of updates are coming in.
  • the second possible solution is to add a sequence number to the update to ensure the most recent sequence number is always used.
  • IPSEC Another operating mode that IPSEC supports is tunneling, where data packets are encapsulated in a new packet as part of a secure connection.
  • a tunnel appears as a virtual interface to the network stack 202.
  • the steps to offload an IPSEC tunnel are similar to the steps to offload an IPSEC connection in the transport mode.
  • an IPSEC header is placed between the IP header and the TCP header.
  • UDP is used to provide a tunnel.
  • the header chain is TCP header to IPSEC header to UDP header to IP header to framing layer header.
  • an inbound descriptor and an outbound descriptor that describe the negotiated security connections are sent to the peripheral device.
  • the descriptors contain the state variables for the connection and other information required to establish the connection.
  • the CACHED and DELEGATED state variables for a tunnel are the same as the transport mode CACHED and DELEGATED state variables.
  • the CONST state variables for a tunnel include source and destination port, local address, remote address, protocol type, and security association variables.
  • a method to offload and upload network stack connections to a peripheral device has been described that maintains a tight synchronization with the host processing unit
  • the method can be used with many protocols.
  • protocols that can be used include TCP, SCTP, etc.

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Security & Cryptography (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Data Exchanges In Wide-Area Networks (AREA)
  • Computer And Data Communications (AREA)
  • Information Transfer Between Computers (AREA)
  • Two-Way Televisions, Distribution Of Moving Picture Or The Like (AREA)
  • Communication Control (AREA)
EP03009321A 2002-04-30 2003-04-24 Method to synchronize and upload an offloaded network stack connection with a network stack Expired - Lifetime EP1361512B1 (en)

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US135630 2002-04-30
US10/135,630 US7181531B2 (en) 2002-04-30 2002-04-30 Method to synchronize and upload an offloaded network stack connection with a network stack

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MXPA03003787A (es) 2005-08-26
ATE396453T1 (de) 2008-06-15
RU2336652C2 (ru) 2008-10-20
US20050182854A1 (en) 2005-08-18
AU2003203727A8 (en) 2003-11-13
US7181531B2 (en) 2007-02-20
KR20030085484A (ko) 2003-11-05
DE60321082D1 (de) 2008-07-03
JP4638658B2 (ja) 2011-02-23
AU2003203727A1 (en) 2003-11-13
CA2425706C (en) 2010-02-16
EP1361512A3 (en) 2005-11-30
BR0301035A (pt) 2004-08-17
KR100938519B1 (ko) 2010-01-25
US20030204631A1 (en) 2003-10-30
JP2004030612A (ja) 2004-01-29
JP2011018373A (ja) 2011-01-27
AU2003203727B2 (en) 2009-04-23
EP1361512A2 (en) 2003-11-12
CN100552626C (zh) 2009-10-21
US7171489B2 (en) 2007-01-30
CA2425706A1 (en) 2003-10-30

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